The Chancellor set out the first projects that will be included in the promised road investment strategy, a £5 billion package to support the roll-out of broadband and a £220 million fund for buses.
Britain is not scheduled to hold an election until 2022, but one is expected in the coming months.
McDonnell said on Saturday he had asked Mark Sedwill, the government's cabinet secretary, to investigate any conflict of interest after former finance minister Philip Hammond said "speculators" who backed Prime Minister Boris Johnson stood to profit from a falling pound in the event of a no-deal Brexit.
He said, "Of course, every government should observe all laws at all times. We're taking a careful look at that law, but we are also very clear that our policy has not changed - we will leave on October 31st", he told the BBC.
Sterling plunged after the Brexit referendum in June 2016 and it is widely expected to slide again if Johnson takes the country out of the European Union on October 31 without a transition deal, something he says he is prepared to do despite efforts by lawmakers to stop him.
He added on McDonnell: "I think (he) is making a fairly political and, dare I say it, fairly speculative attempt to try and throw mud around the House this afternoon".
After almost a decade of deficit-reducing spending cuts under a Conservative-led government, the recently appointed Javid has promised to rewrite the rules that underpin spending.
The new mechanism to define spending and borrowing limits has not yet been agreed, but it is expected to allow higher levels of state-funded infrastructure investment.
Describing it as an Infrastructure Revolution, Javid outlined massive road building plans costing 29 billion pounds and a 5-billion-pound boost for digital infrastructure to improve full fiber broadband. "But the work must start here and now", he will say.
He said: "The prime minister and the Conservative Party have received £726,000 from individuals who back a no-deal Brexit, many involved in hedge funds, in this year alone".